Genetics- Chapter 16

Control of Gene Expression in Bacteria

A gene that encodes a protein that functions in metabolism or biosynthesis or that has a structural role in the cell

Structural gene

A gene that encodes a protein or RNA molecule that interacts with other genes and affects transcription or translation of those sequences

Regulatory gene

The products of __________ genes are RNA molecules or proteins

Regulatory

Bacteria and eukaryotes use __________ genes to control the expression of many of their structural genes

Regulatory

A gene that is expressed continually without regulation is said to be ____________

Constitutive

True or False:

Constitutive genes are regulated

False

A __________ element is a DNA sequence that affects the transcription of other DNA sequences to which it is physically linked

Regulatory

A _ control stimulates gene expression

+

A _ control inhibits gene expression

-

The functional part of a protein

Domain

Amino acids in DNA-binding proteins interact with DNA by forming ________ bonds with DNA bases

Hydrogen

True or False:

Many bacterial genes that have related functions are clustered together and under the control of a single promoter

True

A group of bacterial structural genes that are transcribed together, along with their promoter and additional sequences that control their transcription

Operon

The ______ regulates the expression of the structural genes by controlling transcription

Operon

An ______ is a single transcription unit that includes a series of structural genes, a promoter, and an operator

Operon

_____________ control is usually the most important level of gene regulation

Transcription

A regulator gene helps control the expression of the __________ genes of the operon by increasing or decreasing their transcription

Structural

A _________ protein is produced by a regulator gene and binds to another DNA sequence and controls the transcription of other genes

Regulator

A DNA sequence in an operon to which a regulator protein binds

Operator

__________ genes encode proteins used in metabolism or biosynthesis or cell structure; _________ genes control the transciption of structural genes

Structural; regulator

Transcriptional control in which a regulatory protein is a repressor, binding to DNA and inhibiting translation, is said to be _

-

Transcriptional control in which a regulatory protein is an activator, stimulating transcription, is said to be _

+

A(n) _________ operon is an operon in which transcription is normally off and needs to be turned on

Inducible

A(n) ___________ operon is an operon in which transcription is normally on and needs to be turned off

Repressible

A small molecule that typically binds to the repressor and turns on transcription

Inducer

A(n) __________ protein changes its conformation upon binding to another molecule

Allosteric

True or False:

Enzymes are synthesized only when their substrate is available

True

A small molecule that binds to the repressor and makes it capable of binding to the operator to turn off transcription

Corepressor

The lac operon of E. coli is a _ inducible operon

-

The ___ operon of E. coli regulates lactose metabolism

lac

Components of the lac operon:

The inducer: ___________

The repressor encoding gene: ____

The operon promoter: ____

The operon operator: ____

Allolactose; lacI; lacP; lacO

Structural genes of the lac operon of E. coli:

____ encodes β-galactosidases

____ encodes permease

____ encodes transacetylase

lacZ; lacY; lacA

True or False:

The repression of the lac operon fully shuts down transcription

False

________ actively transports lactose into the cell

Permease

Inside of the cell, _______________ breaks lactose into galactose and glucose

B-galactosidase

In the _______ of lactose, the regulator protein binds to the operator and inhibits transcription

Absence

In the ________ of lactose, lactose is converted into allolactose

Presence

In the presence of allolactose, the lac repressor can not bind to the ________

Operator

A bacterial cell that possesses two copies of some genes

Partial diploid

Efficient transcription of the lac operon only takes place if _______ is present and _______ is absent

Lactose; glucose

Catabolite repression is a form of _ control

+

When there are high levels of _______ present, little transcription of the lac operon takes place

Glucose

The tryptophan operon in E. coli is a _ repressible operon

-

When tryptophan is ___, transcription takes place

Low

When tryptophan is ____, transcription does not take place

High

A type of gene regulation in some bacterial operons in which transcription begins at the transcription start site but terminates prematurely

Attenuation

A protein or RNA/DNA sequence that prevents the termination of transcription

Antiterminator

_________ RNA is a small RNA molecule that base pairs with a complementary DNA or RNA sequence and affects its functioning

Antisense

The regulatory sequence of mRNA molecules where molecules can bind and affect gene expression by influencing the formation of secondary structures of mRNA

Riboswitch

An ______ is a gene cluster controlled by a single promoter that transcribes to a single ___ strand

Operon; RNA

A ________ is an RNA catalyst

Ribozyme